Zalam :
I am using q9400 with gtx 750ti .. Is my CPU bottlenecking.?
Depending on what you are trying to run. I supose its about gaming since you have decent card from the current gen. Also I supose on this card you are trying to play the most modern games on the best graphics settings possible while maintaining nice fps. Without knowing more about your rig- RAM, PSU, MB and so on I will say the following - q9400 is a quad core CPU but if iam not mistaken its from 2008. 4 real cores at 2.66GHz and 6MB L2 cache. Its not bad but for modern games isnt enough. SO yes i think your CPU is bottlenecking. Also how much RAM do you have, what type and in what channel - single, dual or what? That also could be a problem.